Abrupt conduction band shifts in strained quantum wells

ADF Imaging and spatially resolved EELS are used to obtain information about the atomic and electronic structure of Ge-Si quantum well structures. Within the regions which are homogeneous at the 10nm length scale, the obtained bandstructure follows the composition and strain as expected. Within 0.5-1.0 nm of strained interfaces, however, the obtained conduction bandstructure is sharper than the composition profile suggests that it ought to be. I will offer some speculation as to the reasons for this behavior.